On Wed 10-05-23 02:18:45, Kent Overstreet wrote:
> On Wed, May 10, 2023 at 03:07:37AM +0200, Jan Kara wrote:
> > On Tue 09-05-23 12:56:31, Kent Overstreet wrote:
> > > From: Kent Overstreet
> > >
> > > This is used by bcachefs to fix a page cache coherency issue with
> > > O_DIRECT writes.
> > >
On Tue, May 23, 2023 at 09:21:56AM -0700, Christoph Hellwig wrote:
> On Tue, May 23, 2023 at 03:34:31PM +0200, Jan Kara wrote:
> > I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> > remembered that GFS2 has dealt with the same deadlocks - b01b2d72da25
> > ("gfs2: Fix mmap
> > No, that's definitely handled (and you can see it in the code I linked),
> > and I wrote a torture test for fstests as well.
>
> I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> remembered that GFS2 has dealt with the same deadlocks - b01b2d72da25
> ("gfs2: Fix mmap +
On Tue, May 23, 2023 at 03:34:31PM +0200, Jan Kara wrote:
> I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> remembered that GFS2 has dealt with the same deadlocks - b01b2d72da25
> ("gfs2: Fix mmap + page fault deadlocks for direct I/O") - in a different
> way (by prefault
On Tue, May 23, 2023 at 12:35:35PM -0400, Kent Overstreet wrote:
> No, this is fundamentally because userspace controls the ordering of
> locking because the buffer passed to dio can point into any address
> space. You can't solve this by changing the locking heirarchy.
>
> If you want to be able
On Tue, May 23, 2023 at 11:43:32PM -0700, Christoph Hellwig wrote:
> On Tue, May 23, 2023 at 12:35:35PM -0400, Kent Overstreet wrote:
> > No, this is fundamentally because userspace controls the ordering of
> > locking because the buffer passed to dio can point into any address
> > space. You can't
On Tue 23-05-23 12:49:06, Kent Overstreet wrote:
> > > No, that's definitely handled (and you can see it in the code I linked),
> > > and I wrote a torture test for fstests as well.
> >
> > I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> > remembered that GFS2 has dealt
On Wed, May 24, 2023 at 04:09:02AM -0400, Kent Overstreet wrote:
> > Well, it seems like you are talking about something else than the
> > existing cases in gfs2 and btrfs, that is you want full consistency
> > between direct I/O and buffered I/O. That's something nothing in the
> > kernel has eve
On Thu, May 25, 2023 at 01:58:13AM -0700, Christoph Hellwig wrote:
> On Wed, May 24, 2023 at 04:09:02AM -0400, Kent Overstreet wrote:
> > > Well, it seems like you are talking about something else than the
> > > existing cases in gfs2 and btrfs, that is you want full consistency
> > > between direc
On Thu, May 25, 2023 at 10:47:31AM +0200, Jan Kara wrote:
> If we submit direct IO that uses mapped file F at offset O as a buffer for
> direct IO from file F, offset O, it will currently livelock in an
> indefinite retry loop. It should rather return error or fall back to
> buffered IO. But that s
On Thu, May 25, 2023 at 01:58:13AM -0700, Christoph Hellwig wrote:
> On Wed, May 24, 2023 at 04:09:02AM -0400, Kent Overstreet wrote:
> > > Well, it seems like you are talking about something else than the
> > > existing cases in gfs2 and btrfs, that is you want full consistency
> > > between direc
Am Di., 23. Mai 2023 um 15:37 Uhr schrieb Jan Kara :
> On Wed 10-05-23 02:18:45, Kent Overstreet wrote:
> > On Wed, May 10, 2023 at 03:07:37AM +0200, Jan Kara wrote:
> > > On Tue 09-05-23 12:56:31, Kent Overstreet wrote:
> > > > From: Kent Overstreet
> > > >
> > > > This is used by bcachefs to fix
Am Di., 23. Mai 2023 um 18:28 Uhr schrieb Christoph Hellwig
:
> On Tue, May 23, 2023 at 03:34:31PM +0200, Jan Kara wrote:
> > I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> > remembered that GFS2 has dealt with the same deadlocks - b01b2d72da25
> > ("gfs2: Fix mmap + pa
Am Do., 25. Mai 2023 um 10:56 Uhr schrieb Jan Kara :
> On Tue 23-05-23 12:49:06, Kent Overstreet wrote:
> > > > No, that's definitely handled (and you can see it in the code I linked),
> > > > and I wrote a torture test for fstests as well.
> > >
> > > I've checked the code and AFAICT it is all ind
On Fri, May 26, 2023 at 12:25:31AM +0200, Andreas Grünbacher wrote:
> Am Di., 23. Mai 2023 um 18:28 Uhr schrieb Christoph Hellwig
> :
> > On Tue, May 23, 2023 at 03:34:31PM +0200, Jan Kara wrote:
> > > I've checked the code and AFAICT it is all indeed handled. BTW, I've now
> > > remembered that G
Am Fr., 26. Mai 2023 um 01:20 Uhr schrieb Kent Overstreet
:
> On Fri, May 26, 2023 at 12:25:31AM +0200, Andreas Grünbacher wrote:
> > Am Di., 23. Mai 2023 um 18:28 Uhr schrieb Christoph Hellwig
> > :
> > > On Tue, May 23, 2023 at 03:34:31PM +0200, Jan Kara wrote:
> > > > I've checked the code and
On Fri, May 26, 2023 at 02:05:26AM +0200, Andreas Grünbacher wrote:
> Oh, it's just that gfs2 uses one dlm lock per inode to control access
> to that inode. In the code, this is called the "inode glock" ---
> glocks being an abstraction above dlm locks --- but it boils down to
> dlm locks in the en
On Thu, May 25, 2023 at 07:20:46PM -0400, Kent Overstreet wrote:
> > > I'm absolutely not in favour to add workarounds for thes kind of locking
> > > problems to the core kernel. I already feel bad for allowing the
> > > small workaround in iomap for btrfs, as just fixing the locking back
> > > th
On Fri, May 26, 2023 at 01:06:46AM -0700, Christoph Hellwig wrote:
> On Thu, May 25, 2023 at 04:50:39PM -0400, Kent Overstreet wrote:
> > A cache that isn't actually consistent is a _bug_. You're being
> > Obsequious. And any time this has come up in previous discussions
> > (including at LSF), tha
On Fri, May 26, 2023 at 01:10:43AM -0700, Christoph Hellwig wrote:
> On Thu, May 25, 2023 at 07:20:46PM -0400, Kent Overstreet wrote:
> > > > I'm absolutely not in favour to add workarounds for thes kind of locking
> > > > problems to the core kernel. I already feel bad for allowing the
> > > > sm
On Thu, May 25, 2023 at 04:50:39PM -0400, Kent Overstreet wrote:
> A cache that isn't actually consistent is a _bug_. You're being
> Obsequious. And any time this has come up in previous discussions
> (including at LSF), that was never up for debate, the only question has
> been whether it was even
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